1. Field of the Invention
This invention relates to an apparatus for mixing together a plurality of flowable materials, such as a liquid with another liquid, a liquid with a gas, a liquid with a dry granular or powder material, a liquid with solids in a slurry or a suspension, or various combinations of these materials.
2. Background Art
Mixers can be generally classified as either a continuous type or a batch type. In a continuous mixer, a plurality of flowable materials, such as liquids, gases, powders, and the like are supplied at a particular flow rate into a mixing chamber and are mixed by their velocity and turbulence or by mechanical stirring, or both. Known continuous mixers do not always provide sufficient contact between the molecules of the materials to effect complete mixing. If the object of the mixing is a reaction, such as when a reagent is added to adjust the chemistry of acidic mine water, more reagent than is needed for the reaction is used to compensate for the inefficiency in mixing and to achieve as much contact by the reagent as possible. The inefficiency of the mixer results in extra cost from the use of excess reagent as well as the energy involved in operating the mechanical mixer.
In a batch type of mixer, two or more materials are placed in a container and mixed together by stirring, rotation, tumbling or the like. It is also common to mix oxygen with liquids, such as contaminated water, by either surface, turbine or bubble aerators in conjunction with large settling ponds or tanks. Such batch type mixers have several disadvantages. The mixing is rather slow since the materials are fed into the mixer, then mixed for a time period until the entire volume is mixed, and then removed from the mixing chamber. These mixers are also generally large, especially so with settling ponds, since an entire batch is treated at one time. Moreover, batch mixers are not generally efficient in operation.
The mixer disclosed in my previously issued U.S. Pat. No. 4,647,212, entitled "Continuous, Static Mixing Apparatus", solved a number of problems with the prior art mixers. In particular, the mixer disclosed in this patent is a continuous type of mixer which efficiently and thoroughly mixes together a plurality of materials. The mixer is totally static in operation, includes no moving elements, requires little maintenance or downtime, and is relatively simple of construction. In addition, the mixer disclosed in my previously issued patent is flexible in design, can accommodate a variety of specific needs, and can be used in a Variety of system configurations.
However, there are a number of drawbacks to the specific structure disclosed in my Patent No. 4,647,212. In particular, the mixer disclosed in my patent takes a portion of the mixing chamber, between end walls and separate nozzle plates at each end, for entrance chambers or atria for the two incoming fluid streams. The mixing chamber must be made large enough to provide for these entrance chambers or atria between the end plates and the nozzle plates. Moreover, the specific structure includes separate nozzle plates which are mounted within the elongated, cylindrical hollow body of the mixer. Since the pressure of the incoming fluid is applied to the entire surface of the nozzle plates, these nozzle plates must be securely fastened within the hollow body. This is a particular problem where the circumference of each nozzle plate comes in contact with the inner surface of the hollow body. Moreover, the nozzle plates may flex at high pressures and weaken the fastening mechanism. Finally, since the atria or entrance chambers each extend for a considerable distance on either side of the inlets to the nozzle bores, this tends to result in pocketing or trapping of liquids between the end plates and the nozzle plates. This causes a considerable draining problem when the mixer is not in use.
Accordingly, it is an object of the present invention to utilize all of the advantages of the mixer disclosed in my Patent No. 4,647,212, yet overcome certain drawbacks in the particular mixer structure disclosed therein.